Q Bank for Civil Engineer LDCE Exam- Write Short Notes on (20)

Qus. 16. Write short note on 

a. Monsoon Precautions 

Ans:- 1. All catch water drains and side drains must be cleared of silt, vegetation and other obstructions to be ensure free flow and quick drainage of storm water. The waterways of bridge must be cleared of vegetation and other obstruction. If silting is noticed some span, it should be removed to ensure that the full waterways is available for the discharge of flood water, During desilting, care should be taken to remove the silt only up to the bed level. 

2. Protective and river training works must be maintained in good condition and repairs carried out wherever necessary. Scour holes should be filled with boulders. 

3. The High Flood Level (HFL), full supply level (FSL) in the case of canals, and danger level (DL) must be painted. The danger level mark shall painted with bright red band across each pier adjacent to the abutment so as to be clearly visible to the patrolmen, special watchman and Drivers Flood gauges shall be painted on important bridges specified. 

4. Water shall not be allowed to stagnate on the track. For this purpose, cross drains should be provided at regular intervals. In yards, cross drains and longitudinal drains should be cleared/provided to proper grades. 

5. In hilly areas, where there is incidence of falling boulders, a survey should be carried out to locate loose boulders. Such loose boulders should be dropped in a systematic manner. 

6. Selection of patrolman and watchman should be made in accordance with Para 1008 and they must be trained and tested for their knowledge of rules. The duties to be performed by them should be clearly explained to them. The equipment of Patrolmen and other watchman shall be complete in all respects. 

7. Spare trollies should be kept in readiness at he headquarters of the Permanent way inspector and at other stations in the proximity of vulnerable locations. Motor Trollies must be overhauled and kept in fit condition.

7. Rivers in the upstream reaches should be inspected for guarding against possible change in water course. 

7. The prescribed reserve stock of boulders, empty cement bags, wire netting and sand/quarry dust should be kept at specified locations for rushing to site, in case of emergency and should be made good, in case of deficiency. 

Maintenance of PRC sleepers

Ans:- (I) Concrete sleepers should normally be maintained with heavy on track tamers. For spot attention, off track tampers may be used. 

 (ii) Only 30 sleeper spaces are to be opened out at a time between two fully boxed stretches of track of 30 sleeper lengths each in case LWR track exists. 

(III) The concrete sleepers should be compacted well and uniformly to give a good riding surface centre binding of mono block concrete sleepers should be avoided and for that purpose the central 800mm. Of the sleeper should be hard packed. 

(iv) Both ends of concrete sleepers should be painted with anti corrosive paint periodically to prevent corrosion of the exposed ends of pre-stressing wires. 

(v) The laying and maintenance of concrete sleepers should be done by mechanical equipments as far as possible. 

(vi) Wherever casual renewal of concrete sleepers is to be done, normally precautions required for LWR track should be taken. 

(vii) The elastic rail clip should be driven properly to ensure that the leg of the clip is flush with the end face of the insert. Over driving and under driving should be guarded against as this causes eccentric loading on the insulation and this results in their displacement and of the load. 

(viii) vigilant watch should be kept to ensure that not creep takes place in any portion of the concrete sleeper track and there is no excessive movement near SEJ. 

(IX) Rubber pads: It must be ensured that the rubber pads are in correct position.Wherever it is found that the rubber pads have developed a permanent set, these should be replaced by new ones. Such examination can be done at the time of de- stressing. Loss of toe load can also be due to ineffective pads. 

 (x) Insulating liners: Nylon or composite insulating liners used with pandrol clips should be examined periodically for sign of cracking and breakage. Adequate care should be exercised while driving the clip at the time of installation to prevent damage. 

 (xi) Special attention to prevent seizure of elastic rail clips: One of the biggest problems of maintenance of concrete sleeper track is that elastic rail clips get seized with MCI inserts not only in regular maintenance, but also during de- stressing, other incidental works and derailments etc. Following remedial measures are suggested. 

a. Measures to prevent corrosion and seizure of ERCs with M.C.I. inserts : At the base depot, all the elastic rail clips and MCI inserts should be thoroughly cleaned. Grease should then be applied on the central leg of the ERC and eye of the MCI insert and then the clip should be driven at the time of assembly of the service panel. 

b. All the elastic rail clips are to be taken out during service from the MCI inserts and should be cleaned with wire brush and emery paper specially on the central leg. The eyes of the MCI inserts are also to be cleaned of any debris or rusted material the central leg of the ERC should then be applied with proper quality of Grease. 

 c. Distressing of LWR

Ans:- When is distressing Necessary:- Whenever there is abnormal behaviour of LWR as indicated below, distressing should be done: 

i. Gaps at SEJ : whenever the gap observed at SEJ differs beyond limits specified or exceeds the maximum designed gap of SEJ or when stock/tongue rail crosses the mean position. 

ii. After special maintenance operation: After special maintenance operations viz. Deep screening, lifting or lowering of track major realignment of cures sleeper renewals other the casual renewals and rehatibiliation of bridges and formation causing disturbance to track. 

iii. Unusual occurrences: after unusual occurances viz rail fractures or replacement of defective rail/glued joint, damage to SEJ/ Buffer rails, bucking & breaches etc. iv. Temporary repairs: if number of locations where temporary repairs have been done exceed three per km. Procedure for Destressing without use of rail tensors. 

(i) A traffic block of adequate duration say about 3 hours is taken at such a time when the rail temperature is between tm+5 and tm+10c, for 60kg/52kg rail or tm- to- tm+ 5c for lighter rail sections, Before the block is taken a speed restriction of 30 kmph is imposed and fastenings on alternate sleepers loosened. 

(ii) During the block the closure rail are disconnected and the S.E.Js are adjusted to be in the mean position. 

(iii) The sleeper fastenings on both the rails are loosened, starting from the S.E.Js to the centre of LWR iv. The rails are lifted and placed on the rollers at about every 15th sleeper, to permit free expansion the rails are also struck with wooden hammers to help in distressing. 

iv. The rollers are then removed and the fastenings tightened, starting from the centre of LWR towards SEJ the tightening of the fastenings must be completed in the defined temperature range of destressings. 

iv. A cut rail is provided between the S.E.J and LWR keeping adequate provision for thermit welding. 

iv. Thermit welding of joints is done subsequently to complete all the operations of distressing. Destressing of the rails should be done simultaneously. While distressing on curves the rails should be provided with the lateral supports at an interval of 10 sleeper on the inside of curves and at an interval of 30 sleeper on the outside of curve. At time of distressing, a gap of 7 to 8mm should be provided at each of the fish plated joints of the buffer rail assembly. 

d. Winter Precautions

Ans:- Winter Precautions:- 1. Winter de- stressing should be carried out to reduce the temperature forces wherever due, to check the occurrence of Rail/weld fractures and record of such de-stressing should be maintained.

2. Majority of fractures occurs, when the rail temperature is minimum during early hours in the morning. To detect the fractures during winter months, Kerman’s duty roster should be changed to have early morning patrol so that failures, if any can be detected in time, in addition to cold weather patrolling to be carried out as per stipulated instructions. 

3. Gap survey should be done in SWR territory and gap adjustments shoald be done where needed. Creep should be measured and action taken to arrest it. 

4. For urgent temporary repairs of locations of rail/weld fractures, spare joggled fish plates, clamps bolts, wooden blocks should be kept at every km gate lodges, and gang huts. 

5. Shallow screening of pumping joints should be carried out. 

6. The joint sleeper spacing should be rectified wherever required. 

7. Ensure zero missing fittings by recouping deficiency , if any immediately. 

8. No new holes should be drilled without proper equipment and chamfering. All location or the holes in the rails should be visually examined for any cracks. 

e. Maintenance of CMS Xing

Ans:- (i) The procedure followed for inspection and maintenance of ordinary points and Crossings should be followed in the case of CMS crossing also. 

 (ii) Due to heavier weight of the CMS crossing the sleepers under the crossings are likely to develop a concave shape in the central portion tending to minimize the life of wooden sleepers it is therefore, important that the crossing sleepers are well- packed. 

(III) Incorrect gauge at the crossing may lead to excessive wear on the nose or check rail and may result in possible derailment. The gauge, therefore, at the crossing should always be correct; there is likelihood of gauge face of wing rails developing sharp corners due to wear and inadequate flange way clearance which would result in rapid wearing of the wheels passing over them. In such cases the gauge faces should be rounded off to 10 mm radius by grinding. 

(iv) The flange ways of the CMS crossings should be ground to proper radius after it has been in service from 3 weeks to 3 months. Depending on the traffic. A second grinding two or three months later is also recommended as this will increase the life of the crossing before it will need further attention. 

(v) Whenever the metal has flown out on nose or wing rails, the extra metal should be filed in such a way that the contour profile is not disturbed . where filing becomes difficult the only alternative is to try grinding by means of a portable pneumatic or electric grinder taking care that the location does not get excessively heated up . 

(vi) No attempt should be made to make holes in the CMS crossing by flame cutting, as this will lead to cracking of the crossing. 

(vii) When laid in locations subjected to heavy traffic density. a careful watch should be kept to find out development of hair cracks and wavy corrugations. If these develop, the crossing should be replaced and sent for metallurgical investigations.

(viii) After laying the CMS crossing an initial speed restriction of 50 kmph should be imposed for about 3 weeks or the passage of 50,000 axles, The crossings should then be inspected for cracks defects and if they are found to be free from any cracks, defects etc. The speed restrictions may be withdrawn at the discretion of the chief Engineer. 

f. How to arrest the weld failure.

Ans:- 1. In case of welding of rail on cess, full rail length should be supported on at least ten wooden blocks either side of proposed weld and rails should be properly aligned spiked and held in position. Welding should be carried out on proper cess and not on the ballast shoulder. 

2. In case of in-situ welding, rails fastenings of at five sleepers on either side of proposed weld should be loosened. 

3. Ensure that rails are with nil battering & nil hogging at their ends. 

4. Ensure that portions being used match with type and chemistry of rail i.e. weight & UTS. 

5. Rail end should be cleaned with wire brush & k-oil. 

6. Rail ends should be cut straight and square. 

7. Gap should be as per welding technique being used. 

8. Ensure correct alignment of rails prior to welding. 

9. Ensure that prefabricated moulds are as per welding techniques, free from any moisture & cracks. 

10. Pre-fabricated moulds should be dressed with respect to actual rail profile being welding prior to their fixing 

11. Prefabricated mould should be centrally fixed and central lines of two halves of prefabricated moulds should be coinciding with each other. 12. Ensure that mould shoes are in proper shape.

13. Prefabricated mould should be gently inserted / adjusted in mould shoe. 

14. Spatulea should be used for luting of the joint-gap ensure that premixed luting sand is not older than four months from its date of manufacture. 

15. Ensure that no foreign elements are mixed in luting sand. 

16. For proper and uniform preheating of both rail ends, vaporizers should be placed/set at proper height. Maximum height of gooseneck from rail top should be 40mm. 

17. Ensure that crucible is properly dried/charged and respaired with magnasite prior to pouring o portions. 

18. Enusre that thimble is dry and free from moisture and also thimble shape is round and of dia 18-20mm (25mm Technique)and 20-22mm(75mm Technique) 

19. Maximum height of crucible from top of prefabricated mould should be 50mm. 

20. Workability of pressure gauge fitted on petrol tank in case of pre-heating by petrol and gauge fitted on Oxygen & L.P.G. cylinder in case of preheating. With oxy-LPG mixture should be checked before carrying out of welding of rails. 

21. Ensure that portion bags are properly sealed and intact at the time of opening for use. 

22. 90 UTS portion should be used when welding of 72 UTS & 90 UTS rails is being done under unavoidable circumstances. 

23. Portion being used should not be of more then two years old from the date of manufacturing provided packing is intact and there is no entry of moisture. 

24. Portion should be stored in steel box at the site of welding.

25. Parameters of traffic block, preheating pressure and preheating should be adhered as stipulated for AT welding. Table 10.20 Traffic block and pre-heating time for different types of pre-heating

26. Portion should be thoroughly mixed in the pan before pouring it into the crucible for ignition

26. Ensure reaction time after ignition of portion, as 25±3 seconds and portion in the crucible should be covered by crucible cap after start of reaction. 

26. Molten metal should be tapped on completion of reaction and after slag separation. 26. Bottom half of prefab mould and risers should be preserved at the time of demoulding to ensue controlled cooling. 

26. Chipping of hot metal should be done after 4-6 minutes of pouring of molten metal into the gap for 25mm gap joint & 12 minutes for 75 mm gap joint. 

26. In case of in-situ welding newly welded joint should be supported on wooden block joggle fish plated and first train should be passed with restricted speed after rough finishing of joint after 30 minutes of pouring molten metal. 

26. Ensure final finishing of joint within 24 hours of its execution. 26. Ensue that there is no chisel mark on rail surface after final finishing. 

26. Ensure that each weld bears distinctive mark indicating month, year, agency, welder’s code and weld number punched on an aluminium, stop and fixed to the weld with epoxy adhesive at 30mm from joint. No punch marking should be done on the rail and particulars of welds are recorded are per proforma. 26. Ensure that weld are stencilled with welder’s code and particulars of welds are recorded as per proforma circulated by Railway Board. 

26. Repair to crucible shall be done using magnasite 

26. Weld collar should be painted upto 10 cms on either side of weld by usmg correct procedure. 

26. In case of emergency if joint is to be executed in failing temperature use tensor. 

g. Fabrication of Glued joint INSITU.

Ans:- General:- 1. Glued joints are laid at place where insulation of rails as well as continuity of rails is required .

2. Normally Glued joints are fabricated in shop floor and transported to the site however as the glued joints fabricated at the site save effort needed in transportation and also save at least two thermit welds. Welds. Which are a weak link in track. Repairs to a failed/damaged glued joint can also be conveniently done at site, carefully fabricated glued joint in the field can given as good a service as a shop fabricated glued joint. 

Fabrication works:- 1. In case the fabrication is being done in running track, minimum traffic block of 2 hours shall be taken and track protected with banner flag and detonator. Rail should be made free of fittings over as length of 2.00 m on either side. 

2. Grinding of rialto a length of 50cms on either end should be done with the AG-9 grinder and it shall be ensured that no rolling mark, rust dents are in contact with the fishplate. 

3. Both the fishplates shall be ground to make the surface free form dust dents grease etc. 

4. The gap shall be maintained slightly more than 10mm to accommodate the end post (to achieve this tensor shall be applied) 

5. The rail end shall be aligned laterally and vertically with straight edge using suitable wedges. After aligning no hammering/disturbance to ends should be done. 

6. The rail and fishplates surface shall be cleaned with acetone and dried completely. 

7. The resin and hardener shall be thoroughly mixed to get homogeneous mixture. The mixed glue shall be consumed within it pot life (Generally 30 minutes) 

8. A thick layer of glue shall be applied on mating surface of the fishplates simultaneously be two workmen. 

9. One piece of clean glass cloth carrier shall be placed on the fishplates and evenly pressed so that the glue squeezes out through the glass cloth. The oozing shall be uniformity spread over. A layer of glue shall be applied on inside of the insulating channel followed by then placement on the glued glass cloth carrier on the two fishplates. 

10. A layer of glue shall then be applied on the outside of the insulating channel and a clean piece of glass cloth carrier shall be laid. The oozing glue shall be uniformly spread. 

11. Glue shall be applied to both the faces of end posts and placed between the two rail ends. The tensor may be tightened to place the end post firmly if the same is loose due to more gap. Alignment checked again at this stage and corrected i disturbed. 

12. The insulating bushes duly dipped in glue shall be placed in rail holes. The bonding surfaces of the rail shall then be coated with a layer of glue and the fish plates made ready shall be placed in position in contact with the rail web. 

13. H.T.S. bolts washers and nuts well cleaned and free from oil, dust etc. Shall be placed in position and tightened with torque wrench. The torque shall be increased gradually on all the bolts, care shall be taken to tighten inner bolts first and than outer bolts. Finally all the bolts shall be tightened with the torque of 105 kg-M. 

14. The above `operation shall be finished within 45-60 minutes so that minimum 60 minutes setting time is achieved. 

15. About 20 minutes after initial tightening, all the bolts shall be re-tightened with the torque of 105kg-M 

16. The joint shall be finished by covering all the visible edges of glass cloth carrier with glue. 

17. After re-tightening the bolts. Joint is left for setting with tensor in clamped condition.

18. After setting, the removed fittings are restored in position tensor removed and traffic block shall be cancelled. 

19. Before passing the traffic, it shall be ensured that no extra material like settled glue3 etc. Remains on top of the head & gauge face side of the rail. 

20. Traffic may be passed at restricted speed of 30 kmph for about two hours after which the speed restriction shall be relaxed to normal.